Want that bonus? Ditch the Hawaiian shirt

Casual Friday is supposed to be fun and relaxed in the white-collared world. But on Wall Street, there are unwritten rules that must be followed or else...

It's not like wearing a pair of jean shorts could cost you a $500,000 bonus — well, actually, maybe it could. Casual Friday is not your friend. What you choose to wear on this day can't make you, but it can BREAK you.

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In 1996, when I was at Morgan Stanley, they sent around a company-wide email announcing Casual Friday. My first thought was great! My second was, what am I going to wear??? The email didn't go into detail. "Business casual" was the term used.

That morning, I put on my khakis, blue button-down shirt and nice loafers, hopped in a cab and went to the office. I played it safe — right down the middle. We would later call this, "The Wall Street Jumpsuit."

That's one of the most basic rules: Keep it simple. Don't draw attention to yourself. You can mix and match and move things around, but leave the crazy individual fashion statements for the club.

As I made my way to the desk, everyone looked different. It was like when you're in fourth grade and you'd see your elementary teacher at the grocery store. You realize, hey, they're actually a real person! It was like a peek behind the curtain to their personality.

And scrutiny was at an all-time high.

I flipped on my computer and started getting ready for the day. That's when I saw a Hawaiian shirt strolling by. I did a double-take and immediately exchanged a look with my desk-mate Lauren. We both giggled. To some, a Hawaiian shirt might symbolize a fun loving and carefree guy.

But just because you can do it doesn't mean you should. Don't get me wrong, I built an entire career on being different — but it has limits.

A few weeks later, a female co-worker was wearing something that looked like it could be balled up on Kim Kardashian's bedroom floor. It was white and basically see-through. She looked great — maybe too great. Although this was long before Twitter existed, her white shirt was trending throughout the entire company. Employees from different departments were getting emails and then finding excuses to stop by the 37th floor to catch a look.

Beyond the murmuring, sideways glances and damage to your reputation, a Casual Friday faux pas could get you slapped with an unwanted nickname forever (not just during your time at the company). You're branded for life. And you can't recover from this.

So, with the help of some of my friends, here's a list of some of the more infamous nicknames on Wall Street that came straight from Casual Friday:

"Black Jeans." I'm not sure if it was solely because of the color of his jeans. It might have also had something to do with the tightness of them. But this gentleman was called Black Jeans for years. In private, of course. You don't want to be rude.

"Coldplay." The dude wore the shirt once. But it was more of his reaction that created the nickname that would stick for the rest of his time at the company. He adamantly defended himself by saying he didn't like the band, but he liked the colors of the shirt. The lesson here is: Don't defend your mistakes.

"Da Plane!" A woman in Chicago chose to wear a shirt that was fully revealing in the back. All of her peers got to see the monster ink she was representing. Her entire back was tatt'd up. So, taking from the show, "Fantasy Island," they decided the best nickname for her was Tattoo's catch phrase, "Da Plane! Da Plane!"

SFP (a.k.a, "Sorry For Partying"). Thursday nights were epic for this guy and he would always apologize for it the next day. "I'm sorry for partying," he would spout the next morning. And he was really sorry the day he accidentally came to work wearing two different kinds of shoes. This is not considered casual; it's considered still drunk.

JBF ("Just Been F…."). Her hair screamed, "I just had sex!" Apparently her boyfriend's apartment was right near the office and that's where she slept on Thursday nights. You can get a pass for smelling like Taco Bell and Patron, but at least put a comb through your hair.

I'm not kidding when I say these things will stick with you FOR LIFE. If I bumped into Black Jeans on the street today, I'd still call him Black Jeans.

Buttons. Yes, those seemingly benign things on your shirt — they, too, can break you. How many buttons unbuttoned is acceptable? The answer is: Two. (Personally, I'm more of a three-button guy.) Four? BUZZER! Unacceptable. Nobody wants to see your impressive amount of chest hair and the office isn't cocktail hour in the Hamptons. So, unbutton at your own risk.

This is not to diss all casual attire, but rather to say that there is a time and place for your Nantucket Reds, your club logo'd golf shirt, the tight-fitting ensemble and boat shoes without socks. Just not on Wall Street. Not on Casual Friday.

So, the next time a Wall Streeter with a black card steps to the register holding a new wardrobe, they shouldn't be asking themselves: How much will this cost? They should be wondering: What could this potentially cost me if I wear it at the office?

If you don't work on Wall Street, aloha! Enjoy that Hawaiian shirt.

Commentary byTurney Duff, a former trader at the hedge fund Galleon Group. Duff chronicled the spectacular rise and fall of his career on Wall Street in the book, "The Buy Side," and is currently working on his second book, a Wall Street novel.He is also featured on the CNBC show, "The Filthy Rich Guide." Follow him on Twitter @turneyduff.